The Dynamics of Soil Carbon and Nitrogen in a Wet Australian Sclerophyll Forest as Affected by Repeated Prescribed Fires

Abstract

Australia has 155 million hectares of native forests. Trees in Australia's native forests hold about 6.56 billion tonnes of carbon (C) in their biomass, with eucalypt woodlands and open forests containing the most biomass. Historically, fire has been a distinct feature of Australian forests. It is predicted that the frequency and severity of fire in Australia would be increased due to reduced rainfall and high temperature in the near future. Prescribed burning (generally low density fires) has been used as a tool in forest management around the world to reduce fuel load and to protect many of the landscapes from wildfires. However, there are concerns that prescribed fires cause a reduction in soil fertility at sites where the intervals between fires are too short. The extent of fire effects on aboveground ecosystem components and soil varies greatly with fire intensity and frequency. Most studies have been focused on the short-term/immediate effects of fires on soil. The effects of frequency of the long-term repeated fires are largely unknown. The objectives of this study were to examine the effects of different repeated prescribed-burning regimes on a) C and nitrogen (N) storage and b) temporal dynamics of C and N in an Australian forest (Peachester State Forest), using a 39 year-old repeated prescribed burning trial with three treatments: no burning (NB) since 1969, 2 yearly burning (2yrB) and 4 yearly burning (4yrB).